import java.io.IOException;
import java.net.*;
import java.util.Scanner;

public class UdpEchoClient {
    private DatagramSocket socket = null;
    private String serverIP;
    private int serverPost;
    public UdpEchoClient(String serverIP, int serverPost) throws SocketException {
        socket = new DatagramSocket();
        this.serverIP = serverIP;
        this.serverPost = serverPost;
    }
    private void start() throws IOException {
        System.out.println("启动客户端!!!");
        Scanner scanner = new Scanner(System.in);
        while(true){
            //1. 从控制台读取到用户的输入
            System.out.println("->");
            String request = scanner.next();
            //2. 构造出一个 UDP 请求, 发送给服务器
            DatagramPacket requestPacket = new DatagramPacket(request.getBytes(), request.getBytes().length,
                    InetAddress.getByName(this.serverIP), this.serverPost);
            socket.send(requestPacket);
            //3. 从服务器读取到响应
            DatagramPacket responsePacket = new DatagramPacket(new byte[4096], 4096);
            socket.receive(responsePacket);
            String response = new String(responsePacket.getData(), 0, responsePacket.getLength());
            //4. 把响应打印到控制台上
            System.out.println(response);
        }
    }

    public static void main(String[] args) throws IOException {
//        UdpEchoClient client = new UdpEchoClient("118.31.188.7", 9090);
        UdpEchoClient client = new UdpEchoClient("127.0.0.1", 9090);
        client.start();
    }
}
